Amorphous copolyesters

ABSTRACT

Disclosed are amorphous copolyesters having an inherent viscosity (IV) of about 0.5 to 1.1 dL/g measured at a temperature of 25° C. at 0.5 g/dL concentration in a solvent mixture of symmetric tetrachloroethane and phenol having a weight ratio of symmetric tetrachloroethane to phenol of 2:3 comprising (1) a diacid component comprising about 90 to 100 mole percent terephthalic acid residues and 0 to about 10 mole percent isophthalic acid residues; and (2) a diol component comprising about 10 to 70 mole percent 1,4-cyclohexanedimethanol residues and about 90 to 30 mole percent neopentyl glycol residues; wherein the amorphous copolyesters comprises 100 mole percent diacid component and 100 mole percent diol component. The amorphous copolyesters are useful in the manufacture or fabrication of medical devices which have improved resistance to degradation upon exposure to lipids, as a profile produced by profile extrusion and as an injection molded article. Also, a method of melt processing the amorphous copolyester is disclosed which allows for performing a minimal drying or no drying of the copolyester prior to melt processing.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.10/808,070, filed Mar. 24, 2004 now U.S. Pat. No. 7,026,027 which is acontinuation-in-part of application Ser. No. 10/743,112 filed Dec. 22,2003, now abandoned which is a continuation-in-part of application Ser.No. 10/195,267 filed Jul. 15, 2002, now abandoned which claims thebenefit of U.S. Provisional Application Ser. No. 60/306,221 filed Jul.18, 2001.

TECHNICAL FIELD OF THE INVENTION

This invention relates to amorphous copolyesters derived from1,4-cyclohexanedimethanol and neopentyl glycol. More particularly, thisinvention relates to such copolyesters that have a combination of uniqueproperties and to shaped articles fabricated therefrom such as profileextrusions and medical equipment.

BACKGROUND OF THE INVENTION

Amorphous copolyesters comprising terephthalic acid (T) residues anddiol residues comprising varying ratios of 1,4-cyclohexanedimethanol(CHDM) residues and ethylene glycol (EG) residues are well known in theplastics marketplace. As used herein, the abbreviation PETG refers tocopolyesters comprising terephthalic acid residues as the diacid residuecomponent and a diol residue component comprising up to 50 mole percentCHDM residues with the remainder EG residues. PCTG refers tocopolyesters comprising T residues and a diol residue componentcomprising greater than 50 mole percent CHDM residues with the remainderbeing EG residues. Copolyesters comprising T residues and diol residuescomprising about 20 to 70 mole percent CHDM residues and about 80 to 30mole percent EG residues are amorphous. The term “amorphous” as definedherein means a polyester that does not exhibit a substantial crystallinemelting point when scanned by differential scanning calorimetry (DSC) ata rate of 20° C./minute.

Amorphous copolyesters in general possess a combination of desirableproperties for many applications. These properties include excellentclarity and color, toughness, ease of processing, and chemicalresistance. Accordingly, amorphous copolyesters are known to be usefulfor the manufacture of extruded sheet, packaging materials, and partsfor medical devices, etc. Application in transparent medical partsrequires resistance to craze formation and mechanical failure whenexposed to lipid and/or isopropyl alcohol (IPA) solutions. Whereasamorphous copolyesters are known in the art to have good resistance tothese chemicals and are widely applied in these applications, crazeformation occurs at high strains and is thus an area of neededimprovement. Consequently, there is an unmet need for amorphouscopolyesters that under high strains have improved resistance to lipidand IPA solutions.

There is also an important need for amorphous copolyesters that haveimproved resistance to hydrolytic degradation. U.S. Pat. No. 5,656,715discloses that copolyesters containing a diol residue componentcomprising 60 to 100 mole percent residues of 1,4-cyclohexanedimethanolexhibit improved resistance to hydrolytic degradation.

Neopentyl glycol (NPG-2,2-dimethylpropane-1,3-diol) has been used incombination with EG and terephthalic acid to form amorphouscopolyesters. However, the combination of NPG and CHDM as the diolcomponent of copolyesters has received minimal attention. Several earlyreferences disclose copolyesters comprising both CHDM and NPG residuesand terephthalic acid residues. Example 46 of U.S. Pat. No. 2,901,466describes a copolyester of unknown composition that was reported to havea crystalline melting point of 289-297° C. U.S. Pat. No. 3,592,875discloses copolyester compositions that contain both NPG and CHDMresidues with an added polyol present for branching. U.S. Pat. No.3,592,876 discloses polyester compositions that contain EG, CHDM and NPGresidues with the NPG residue level limited to up to 10 mole percent.U.S. Pat. No. 4,471,108 discloses low molecular weight polyesters someof which contain CHDM and NPG residues, but also contain amultifunctional branching agent. U.S. Pat. No. 4,520,188 describes lowmolecular weight copolyesters comprising mixtures of aliphatic andaromatic acid residues with both NPG and CHDM residues present. JapanesePatent Publication JP 3225982 B2 discloses amorphous copolyesters whichare said to be useful in the formulation of coating compositions forsteel sheet. The disclosed copolyesters comprise a diacid componentcomprising mixtures of aliphatic and aromatic acid residues and a diolcomponent comprising NPG and CHDM residues.

U.S. Pat. No. 4,551,403 discloses low molecular weight polyesters thatare used as binders or as the matrix resin for photosensitive materialsfor electrophotography. Example 1 of this patent discloses thepreparation of a polymer from dimethyl terephthalate, neopentyl glycoland 1,4-cyclohexanedimethanol. The polymer is said to have a reducedviscosity of 0.35 as measured at 30° C. in tetrachloroethane at apolymer concentration of 0.5%. The reduced viscosity of 0.35 correspondsto an inherent viscosity as defined herein of 0.29 dL/g using equationsprovided by F. W. Billmeyer, Textbook of Polymer Science, John Wiley &Sons, (1971) page 84. The low molecular weight polyesters disclosed byU.S. Pat. No. 4,551,403 are not useful for producing shaped articles byinjection molding or extrusion procedures.

EP-A1-411,136 discloses copolyesters comprising diacid residuescomprising mainly of terephthalic acid residues and glycol residuescomprising 15 to 85 mole percent C-2 to C-16 aliphatic diol residues and85 to 15 mole percent 1,4-cyclohexanedimethanol residues wherein 80 molepercent of the cyclohexanedimethanol residues are in the trans form. Itis believed that the properties of the copolyesters specificallyexemplified in EP-A1-411,136 are inferior to the copolyesters describedherein. More specifically, the copolyesters described herein possessimproved melt strength and resistance to hydrolysis as compared to thecopolyesters of the examples of EP-A1-411,136.

SUMMARY OF THE INVENTION

We have discovered that amorphous polyesters derived from terephthalicacid, CHDM and NPG are valuable compositions useful for the manufactureof medical devices that exhibit improved resistance to degradation uponexposure to lipids. The amorphous copolyesters provided by the presentinvention have an inherent viscosity (IV) of about 0.5 to 1.1 dL/gmeasured at a temperature of 25° C. at 0.5 g/dL concentration in asolvent mixture of symmetric tetrachloroethane and phenol having aweight ratio of symmetric tetrachloroethane to phenol of 2:3 andcomprise:

-   (1) a diacid component comprising about 90 to 100 mole percent    terephthalic acid residues and 0 to about 10 mole percent    isophthalic acid residues; and-   (2) a diol component comprising about 10 to about 70 mole percent    1,4-cyclohexanedimethanol residues and about 90 to about 30 mole    percent neopentyl glycol residues;    wherein the amorphous copolyesters comprises 100 mole percent diacid    component and 100 mole percent diol component.

Another embodiment of the present invention concerns a shaped articlesuch as an extruded profile or an extruded or injection molded medicaldevice having improved resistance to degradation from exposure to lipidswherein the medical device comprises an amorphous copolyester having aninherent viscosity (IV) of at least about 0.5 dL/g measured at atemperature of 25° C. at 0.5 g/dL concentration in a solvent mixture ofsymmetric tetrachloroethane and phenol having a weight ratio ofsymmetric tetrachloroethane to phenol of 2:3 and comprising:

-   (1) a diacid component comprising about 90 to 100 mole percent    terephthalic acid residues and 0 to about 10 mole percent    isophthalic acid residues; and-   (2) a diol component comprising about 10 to about 70 mole percent    1,4-cyclohexanedimethanol residues and about 90 to about 30 mole    percent neopentyl glycol residues;    wherein the amorphous copolyesters comprises 100 mole percent diacid    component and 100 mole percent diol component.

In still another embodiment of the present invention, a method of meltprocessing an amorphous copolyester having a moisture content prior tomelt processing of 0.02 weight % or more comprises the steps of:

-   (a) prior to melt processing, performing a minimal drying or no    drying of the copolyester such that the copolyester has a moisture    content of 0.02 weight % or more prior to melt processing, and-   (b) melt processing the copolyester, wherein the copolyester has an    inherent viscosity (IV) of about 0.5 to 1.1 dL/g measured at a    temperature of 25° C. at 0.5 g/dL concentration in a solvent mixture    of symmetric tetrachloroethane and phenol having a weight ratio of    symmetric tetrachloroethane to phenol of 2:3 and comprises:    -   (1) a diacid component consisting essentially of about 90 to 100        mole percent terephthalic acid residues and 0 to about 10 mole        percent isophthalic acid residues; and    -   (2) a diol component consisting essentially of about 10 to about        70 mole percent 1,4-cyclohexanedimethanol residues and about 90        to about 30 mole percent neopentyl glycol residues,        wherein the copolyester is based on 100 mole percent diacid        component and 100 mole percent diol component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the melt viscosity shear rate curve at 260° C. for PETG,PROVISTA™, and the amorphous copolyester of the present inventiondescribed in Example 10. FIG. 2 shows the melt viscosity shear ratecurve at 260° C. for PETG, PROVISTA™, and the amorphous copolyester ofthe present invention described in Example 8.

DESCRIPTION OF THE INVENTION

Copolyesters comprising about 90 to 100 mole percent terephthalic acid(T) residues, 0 to about 10 mole percent isophthalic acid residues,1,4-cyclohexanedimethanol (CHDM) residues, and neopentyl glycol (NPG)residues are amorphous in the approximate composition ranges of about 10to about 70 mole CHDM and about 90 to about 30 mole percent NPG. Theseunique amorphous copolyesters show surprisingly improved resistance tocrazing when exposed to lipids or IPA. In addition, the combination ofCHDM and NPG as comonomer diols in the copolyesters of the presentinvention, results in copolyester backbones that exhibit enhancedstability to hydrolysis for the amorphous composition range. The presentcopolyesters having sufficient molecular weight to be molding orextrusion grade plastics and based solely on CHDM and NPG as diols, arenot known. In addition, it is unexpected that the addition of NPG to acopolyester would improve resistance to lipids and IPA.

The amorphous copolyesters of the present invention may be prepared byconventional polymerization processes known in the art, such as theprocedures disclosed in U.S. Pat. Nos. 4,093,603 and 5,681,918. Examplesof polycondensation processes useful in the present invention includemelt phase processes conducted with the introduction of an inert gasstream, such as nitrogen, to shift the equilibrium and advance to highmolecular weight or the more conventional vacuum melt phasepolycondensations, at temperatures in the range of from about 240 to300° C. or higher which are practiced commercially. The terephthalic andisophthalic acid residues of the copolyesters may be derived from eitherthe dicarboxylic acids or ester-producing equivalents thereof such asesters, e.g., dimethyl terephthalate and dimethyl isophthalate, or acidhalides, e.g. acid chlorides. Although not required, conventionaladditives may be added to the copolyesters of the invention in typicalamounts. Examples of such additives include pigments, colorants,stabilizers, antioxidants, extrusion aids, slip agents, carbon black,flame retardants and mixtures thereof.

The polymerization reaction may be carried out in the presence of one ormore conventional polymerization catalysts. Typical catalysts orcatalyst systems for polyester condensation are well-known in the art.Suitable catalysts are disclosed, for example, in U.S. Pat. Nos.4,025,492, 4,136,089, 4,176,224, 4,238,593, and 4,208,527, thedisclosures of which are herein incorporated by reference. Further, R.E. Wilfong, Journal of Polymer Science, 54, 385 (1961) describes typicalcatalysts, which are useful in polyester condensation reactions.Preferred catalyst systems include Ti, Ti/P, Mn/Ti/Co/P, Mn/Ti/P,Zn/Ti/Co/P, Zn/Al. When cobalt is not used in the polycondensation,copolymerizable toners may be incorporated into the copolyesters tocontrol the color of these amorphous copolyesters so that they aresuitable for the intended applications where color may be an importantproperty. In addition to the catalysts and toners, other additives, suchas antioxidants, dyes, etc. may be used in the copolyesterifications.

The copolyesters of the invention have an inherent viscosity (IV) of atleast about 0.5 dL/g, preferably about 0.5 to 1.1 dL/g, measured at atemperature of 25° C. at 0.5 g/dL concentration in a solvent mixture ofsymmetric tetrachloroethane and phenol having a weight ratio ofsymmetric tetrachloroethane to phenol of 2:3. In one embodiment of theinvention, the diacid component of the amorphous copolyester consistsessentially of about 90 to 100 mole percent terephthalic acid residuesand 0 to about 10 mole percent isophthalic acid residues; and the diolcomponent consists essentially of about 10 to about 70 mole percent1,4-cyclohexanedimethanol residues and about 90 to about 30 mole percentneopentyl glycol residues. Preferably, the diacid component consistsessentially of at least 95 mole percent and more preferably 100 molepercent terephthalic acid. The diol component preferably consistsessentially of residues of about 30 to about 70 mole percent or, morepreferably, about 35 to about 60 mole percent, CHDM residues and about70 to about 30 mole percent or, more preferably, about 40 to about 65mole percent, NPG residues. The most preferred copolyesters have an IVof about 0.6 to about1.1 dL/g and comprise:

-   (1) a diacid component consisting essentially of terephthalic acid    residues; and-   (2) a diol component consisting essentially of about 35 to about 60    mole percent 1,4-cyclohexanedimethanol residues and about 40 to    about 65 mole percent neopentyl glycol residues;    wherein the amorphous copolyesters comprises 100 mole percent diacid    component and 100 mole percent diol component.

The copolyesters of the invention can be molded and extruded usingconventional melt processing techniques to produce the shaped article ofour invention. The copolyesters are particularly useful in themanufacture of small and intricately shaped articles such as tubing usedfor handling and transporting medical fluids, etc. The lipid resistanceof the copolyesters of our invention under external strain renders thecopolyesters particularly useful in the manufacture of shaped articlesincluding medical devices such as tubes, pump housings, connectors, etc.where lipid resistance is important. Such medical devices may betransparent. The shaped articles manufactured from the copolyesters ofthis invention possess improved resistance to degradation by medicallipid solutions such as Liposyn II 20% intravenous fat emulsion. Theimproved resistance to degradation is manifested by retention ofelongation to break values (retention of toughness) and significantreduction of visual crazing in molded test bars as shown in the examplesbelow.

The shaped articles may be produced according to conventionalthermoplastic processing procedures such as injection molding,calendaring, extrusion, blow molding, extrusion blow molding, androtational molding. The amorphous copolyesters of the present inventionderived from CHDM and NPG exhibit improved hydrolytic stability atvarious melt temperatures. In the conversion of the copolyesters intoshaped articles, the moisture content of the copolyester typically isreduced to less than about 0.02% prior to melt processing.

Preferably, prior to melt processing, the minimal drying is performed byconventional methods for less than 2 hours at 60 to 100° C. For theminimal drying, a desiccant bed with forced dehumidified air at 60° C.to 100° C. is preferred. Even more preferably, there is no drying of thecopolyester prior to melt processing.

The melt viscosity versus shear rate relationship in polymers is a veryimportant property of polymeric materials. One useful meltviscosity/shear rate relationship is shear thinning. Shear thinningoccurs when the melt flow is non-Newtonian and shows a reversibledecrease in viscosity with increasing shear rate. Shear thinningcharacteristics are very important for allowing the processing ofinjection molded and extruded parts and sheets, such as profiles.Profile extrusion is an extrusion process where special dies are used toproduce articles of asymmetrical shapes. House siding, plastic tubes,channels, baseboard moldings, etc. are examples of profile extrudedparts and are referred to as profiles. Generally amorphous polymers areused in profile extrusion to avoid the shrinking that takes place duringcrystallization processes. The asymmetric nature of the products fromthis process requires special resin properties such as high meltstrength at low melt viscosities and shear thinning melt rheology. Theamorphous copolyesters of the present invention exhibit improved shearthinning behavior.

Referring to the accompanying Figures, FIG. 1 shows melt viscosity shearrate curves at 260° C. for several polymers: (1) PETG is a copolyestercomprises a diacid component comprising 100 mole percent terephthalicacid residues and a diol component comprising 69 mole percent ethyleneglycol residues and 31 mole percent CHDM residues and is commerciallyavailable as EASTAR® 6763 Copolyester from Eastman Chemical Company; (2)PROVISTA™ copolyester (also available from Eastman Chemical Company),which is specifically designed to shear thin by adding branching agents,has a composition similar to PETG; and (3) the copolyester of Example 10of the present invention. Surprisingly, Example 10 exhibits a shearthinning behavior that resembles the PROVISTA™ copolyester and not thePETG. Similarly, FIG. 2 shows melt viscosity shear rate curves at 260°C. for the copolyester of Example 8 which shear thins like PROVISTA™copolyester and not PETG copolyester. For the curves constituting FIGS.1 and 2, the complex viscosity was determined by a Rheonmetrics DynamicAnalyzer (RDA II) with 25 mm diameter parallel plates, 1 mm gap and 10%strain at 260° C. The samples were dried at 60° C. for 24 hours in avacuum oven before the frequency sweep test.

Thus, based on the shear thinning properties described in FIGS. 1 and 2,another embodiment of the present invention is a profile produced byprofile extrusion comprising an amorphous copolyester composition havingan inherent viscosity of about 0.5 to 1.1 dL/g and comprising:

-   -   (1) a diacid component consisting essentially of about 90 to 100        mole percent terephthalic acid residues and 0 to about 10 mole        percent isophthalic acid residues; and    -   (2) a diol component consisting essentially of about 10 to about        70 mole percent 1,4-cyclohexanedimethanol residues and about 90        to about 30 mole percent neopentyl glycol residues;        wherein the amorphous copolyesters comprises 100 mole percent        diacid component and 100 mole percent diol component.

Further, another embodiment is an injection molded article comprising anamorphous copolyester consisting essentially of an acid component ofresidues of at least 90 mole percent terephthalic acid and a glycolcomponent of residues of about 10 to about 70 mole percent1,4-cyclohexanedimethanol and about 90 to about 30 mole percentneopentyl glycol, based on 100 mole percent acid component and 100 molepercent glycol component.

The copolyesters of the invention also may be used to manufacture shapedarticles by extrusion blow molding processes. Such processes typicallycomprise the steps of (1) extruding a copolyester through a die to forma tube of molten copolyester; (2) positioning a mold having the desiredfinished shape around the tube of molten copolyester; and (3)introducing a gas into the tube of molten copolyester, causing theextrudate to stretch and expand to fill the mold.

EXAMPLES

The following Examples are intended to illustrate, but not limit, thescope of the present invention. The inherent viscosities were measuredat a temperature of 25° C. at 0.5 g/dL concentration in a solventmixture of symmetric tetrachloroethane and phenol having a weight ratioof symmetric tetrachloroethane to phenol of 2:3. The 2^(nd) cycle glasstransition temperatures were determined according to DSC at a heatingrate of 20° C./min to a temperature of 280-300° C., quenching in liquidnitrogen to 0° C., and then rerunning the sample and recording the Tg asthe 2^(nd) cycle glass transition temperature. Final copolyestercompositions were determined by proton NMR analysis on a 600 MHz JEOLinstrument.

Example 1

A copolyester comprising a diacid component consisting of 100 molepercent terephthalic acid residues and a diol component consisting of 66mole percent CHDM residues and 34 mole percent NPG residues (hereinafterreferenced as 100T/85CHDM/15NPG) was prepared. Dimethyl terephthalate(DMT; 77.6 g, 0.4 mole), NPG (28.91 g, 0.28 moles), CHDM (46.37 g, 0.32moles), and 1.49 ml of a solution containing 15 g of titaniumtetraisopropoxide in 250 ml of n-butanol were added to a 500 mlsingle-neck, round-bottom flask. The flask was immersed in a Belmontmetal bath that was pre-heated to 200° C. Immediately after the flaskwas immersed the temperature set point was increased to 220° C., andheld for 1 hour. After the hour at 220° C. the temperature was increasedto 260° C., and held for 30 minutes. After this time the theoreticalamount of methanol was collected. The pressure in the flask then wasreduced from atmospheric to 0.5 Torr. When the pressure had been reducedto 0.5 Torr the temperature set point was raised to 280° C. Stirring wasreduced as the viscosity increased until a stir rate of 15 revolutionsper minute (RPM) was obtained. The vacuum was discontinued and nitrogenwas bled into the flask. The polymer was allowed to solidify by coolingto a temperature below Tg, removed from the flask and ground to passthrough a 3 mm screen. The inherent viscosity of the polymer was 0.895dL/g. The polymer had a 2^(nd) cycle Tg of 87.82° C. Compositionalanalysis (by NMR) showed the diol component of the copolyester consistedof 66.1 mole percent CHDM residues and 33.9 mole percent NPG residues.

Example 2

A copolyester having the composition 100T/61CHDM/39NPG was prepared. DMT(77.60 g, 0.40 moles), NPG 33.70 grams (0.33 moles) of NPG, 39.74 grams(0.28 moles) of CHDM, and 1.49 ml of a solution containing 15 grams oftitanium tetraisopropoxide in 250 ml of n-butanol were added to a 500 mlsingle neck round bottom flask and reacted and polymerized according tothe procedure described in Example 1. The inherent viscosity of thepolymer was 0.930 dL/g. The polymer had a 2^(nd) cycle Tg of 86.70° C.with no crystalline melting point observed, and compositional analysisshowed that the diol component of the copolyester consisted of 61.4 molepercent CHDM residues and 38.6 mole percent NPG residues.

Example 3

A copolyester having the composition 100T/56CHDM/44NPG was prepared. DMT(77.6 g, 0.40 moles), NPG (38.48 g, 0.37 moles), CHDM (33.12 g, 0.23moles), and 1.47 ml of a solution containing 15 g of titaniumtetraisopropoxide in 250 ml of n-butanol were added to a 500 ml,single-neck, round-bottom flask and reacted and polymerized according tothe procedure described in Example 1. The inherent viscosity of thepolymer was 0.938 dL/g. The polymer had a 2^(nd) cycle Tg of 85.90° C.with no crystalline melting point observed, and compositional analysisshowed that the diol component of the copolyester consisted of 55.8 molepercent CHDM and 44.2 mole percent NPG residues.

Example 4

A copolyester having the composition 100T/45CHDM/55NPG was prepared. DMT(77.60 g, 0.4 moles), NPG (43.26 g, 0.42 moles), CHDM (26.50 g, 0.18moles), and 1.44 ml of a solution containing 15 g of titaniumtetraisopropoxide in 250 ml of n-butanol were added to a 500 ml singleneck round bottom flask and reacted and polymerized according to theprocedure described in Example 1. The inherent viscosity of the polymerwas 0.897 dL/g. The polymer had a 2^(nd) cycle Tg of 83.66° C. with nocrystalline melting point observed, and compositional analysis showedthe diol component of the copolyester consisted of 44.7 mole percentCHDM and 55.3 mole percent NPG residues.

Example 5

A copolyester having the composition 100T/32CHDM/68NPG was prepared. DMT(77.60 g, 0.4 moles), NPG (48.05 g, 0.46 moles), CHDM (19.87 g, 0.14moles), and 1.42 ml of a solution containing 15 g of titaniumtetraisopropoxide in 250 ml of n-butanol were added to a 500 ml singleneck round bottom flask and reacted and polymerized according to theprocedure described in Example 1. The inherent viscosity of the polymerwas 1.143 dL/g. The polymer had a 2^(nd) cycle Tg of 82.43° C. with nocrystalline melting point observed, and compositional analysis showedthe diol component of the copolyester consisted of 32.3 mole percentCHDM and 67.7 mole percent NPG residues.

Example 6

A copolyester having the composition 100T/21CHDM/79NPG was prepared. DMT(77.60 g, 0.4 moles), NPG (52.83 g, 0.51 moles), CHDM (13.25 g, 0.09moles), and 1.40 ml of a solution containing 15 g of titaniumtetraisopropoxide in 250 ml of n-butanol were added to a 500 ml singleneck round bottom flask and reacted and polymerized according to theprocedure described in Example 1. The inherent viscosity of the polymerwas 0.925 dL/g. The polymer had a 2^(nd) cycle Tg of 80.30° C. with nocrystalline melting point observed, and compositional analysis showedthe diol component of the copolyester consisted of 21.4 mole percentCHDM and 78.6 mole percent NPG residues.

Example 7

A copolyester having the composition 100T/15CHDM/85NPG was prepared. DMT(77.60 g, 0.4 moles), NPG (57.62 g, 0.55 moles), CHDM (6.62 g, 0.05moles), and 1.37 ml of a solution containing 15 g of titaniumtetraisopropoxide in 250 ml of n-butanol were added to a 500 ml singleneck round bottom flask and reacted and polymerized according to theprocedure described in Example 1. The inherent viscosity of the polymerwas 0.863 dL/g. The polymer had a 2^(nd) cycle Tg of 77.78° C. with nocrystalline melting point observed, and compositional analysis showedthe diol component of the copolyester consisted of 14.6 mole percentCHDM and 85.4 mole percent NPG residues.

Example 8

A copolyester having the composition 100T/67CHDM/33NPG was manufacturedin a batch pilot plant reactor. DMT (10.215 kg, 22.5 pounds), NPG (4.495kg, 9.9 pounds), CHDM (5.153 kg, 11.35 pounds), and 53.4 g of a solutionof titanium isopropoxide in n-butanol were charged into a 68.13 liter(18-gallon) batch reactor with intermeshing spiral agitators and adistillation column. The agitators were operated forward for 50 minutesand then reversed for 10 minutes. The internal temperature was increasedto 200° C. and held for 2 hours. The temperature then was increased to260° C. and held for 30 minutes. At this time, the weight of distillatewas recorded and the temperature was increased to 280° C. Upon reaching280° C. the weight of distillate again was recorded. The agitator waschanged to switch directions every 6 minutes, and vacuum was applied ata rate of 13 Torr/minute until full vacuum (0.5 Torr) was reached. Thepolymerization mixture was maintained for 25 minutes at 45 rpm, and thenmaintained for 15 minutes at 10 rpm. The copolyester thus obtained thenwas immediately extruded and chopped into pellets. The polymer had aninherent viscosity of 0.791 dL/g, and a 2^(nd) cycle Tg of 87.48° C.with no crystalline melting point observed. Compositional analysis (byNMR) showed the diol component of the copolyester consisted of 67.4 molepercent CHDM residues and 32.6 mole percent NPG residues. The colorvalues, using the CIE lab color system, were as follows: L*82.28,a*−0.44, b*3.80.

Example 9

A copolyester having the composition 100T/45CHDM/55NPG was produced in abatch pilot plant reactor. DMT (10.669 kg, 23.5 pounds), NPG (6.220 kg,13.7 pounds), CHDM (3.223 kg, 7.1 pounds), and 53.4 g of a solution oftitanium isopropoxide in n-butanol were charged into a 68.13 liter(18-gallon) batch reactor with intermeshing spiral agitators and adistillation column. After charging the raw materials, the manufacturingprocedure described in Example 10 was repeated. The resulting polymerhad an inherent viscosity of 0.844 dL/g, and a 2^(nd) cycle Tg of 84.08°C. with no crystalline melting point observed. Compositional analysis(by NMR) showed the diol component of the copolyester consisted 45.4mole percent CHDM residues and 54.6 mole percent NPG residues. The colorvalues were as follows: L*83.19, a*−0.27, b*3.97.

Example 10

Example 9 was repeated except that the polycondensation was modified toproduce a copolyester having a lower IV. After reaching full vacuum (0.5Torr), the agitator was held at 25 rpm for only 30 minutes, and thenheld for 15 minutes at 10 rpm. The copolyester polymer then wasimmediately extruded and chopped into pellets. The copolyester polymerhad an inherent viscosity of 0.713 dL/g, and a 2^(nd) cycle Tg of 83.41°C. with no crystalline melting point observed. Compositional analysis(by NMR) showed the diol component of the copolyester consisted of 44.1mole percent CHDM and 55.9 mole percent NPG. The color values were asfollows: L*82.79, a*−0.40, b*3.15.

The resistance of the following amorphous copolyesters to attack ordegradation by lipid solutions was evaluated:

-   Copolyester I: PETG 6763, a commercially-available amorphous    polyester wherein the diacid component consists of 100 mole percent    terephthalic acid residues and the diol component consisting of    about 69 mole percent EG residues and 31 mole percent CHDM residues;    IV=0.71.-   Copolyester II: PCTG 5445, a commercially-available amorphous    polyester wherein the diacid component consists of 100 mole percent    terephthalic acid residues and the diol component consisting of    about 38 mole percent EG residues and 62 mole percent CHDM residues;    IV=0.72.-   Copolyester III: Amorphous copolyester of Example 8.-   Copolyester IV: Amorphous copolyester of Example 9.    Standard tensile test bars (ASTM-D638) of each of the copolyesters    I, II, III, and IV were prepared by injection molding. The bars were    placed on three-point-bend strain rigs at fixed strains of 0, 0.5,    1.5 and 2.7% while simultaneously being exposed to Liposyn II 20%    intravenous fat emulsion (lipid solution) for 72 hours. Exposure to    the lipid solution was accomplished by placing a 2.54 mm×1.77 mm (1    inch×0.5 inch) patch of filter paper over the center of the bar and    saturating the patch with the lipid solution initially and then    rewetting several times a day. The treated bars were then subjected    to tensile testing according to ASTM D638. The results of these    tensile tests are shown in Table I wherein the values given for the    experimental strain conditions (Condition Strain), Yield Strain, and    Elongation at Break are percentages. Yield Stress and Break Stress    are given in megapascals. Each test bar was inspected before and    after the evaluation and given a rating of A=no change, B=slightly    crazed, C=moderately crazed, and D=severely crazed. Similar    resistance tests were run with IPA instead of lipid, with these    results shown in Table II wherein the values are the same as those    for Table I. The control represents samples prior to contact with    lipid solution. An inspection of Tables I and II clearly shows that    the amorphous copolyester of the present invention exhibit better    overall performance than the corresponding commercial amorphous    copolyester I and II. The superior performance is manifested, in    general, by the maintenance of a satisfactory appearance and the    maintenance of high elongation to break after exposure to the lipid    while under strain.

TABLE I Condition Yield Elongation Yield Break Copolyester Strain Strainto Break Stress Stress Appearance I Control 5.3 167 48.6 29.2 I 0 5.365.4 51.1 25.5 A I 0.5 5.3 63.2 50.5 25.1 A I 1.5 5.3 40 51.5 25.2 D I2.7 5.2 51.3 49.8 25.9 B II Control 4.7 285 43.4 40.7 II 0 — — — — — II0.5 4.9 289.5 46.7 43.8 A II 1.5 4.9 296.0 46.8 43.3 A II 2.7 — 6.9 —29.5 D III Control 5.7 178.9 43.8 46.8 III 0 5.3 154.9 45.1 43.1 A III0.5 5.3 148.3 45 41.7 A III 1.5 5.4 137.7 45.6 40.9 C III 2.7 5.5 140.544.9 42.1 B IV Control 5.3 134.1 47.4 42.9 IV 0 5 102.9 48.4 36.4 A IV0.5 5.1 99.6 48.8 37.9 A IV 1.5 5.2 24.7 49 36.6 C IV 2.7 5.2 18.1 4836.9 C

TABLE II Condition Yield Elongation Yield Break Copolyester StrainStrain to Break Stress Stress Appearance I Control 5.3 167 48.6 29.2 I 05.3 79 50.5 25.5 A I 0.5 5.3 36.7 50.3 25.2 C I 1.5 5.3 61.7 45.6 25.1 CI 2.7 7 26.6 41.1 25.9 D II Control 4.7 285 43.4 40.7 II 0 — — — — — II0.5 5 287.7 46.3 43.5 D II 1.5 5.1 296.0 38.1 40.2 D II 2.7 7.3 6.9 33.239.5 D III Control 5.7 178.9 43.8 46.8 III 0 5.1 161 45.1 44.7 A III 0.55.2 159.4 44.8 43.8 B III 1.5 5.6 125 44.7 38.9 C III 2.7 5.7 150 42.142.9 D IV Control 5.3 134.1 47.4 42.9 IV 0 5.1 114.9 48.1 38.1 A IV 0.55.1 104.5 48.3 36.9 B IV 1.5 4.3 4.3 42.5 42.5 C IV 2.7 5.2 5.2 36.436.4 D

Example 11

A copolyester having the composition 100T/64CHDM/36NPG was produced in abatch pilot plant reactor. DMT (10.215 kg, 22.5 pounds), NPG (4.495 kg,9.9 pounds), CHDM (5.153 kg, 11.35 pounds), and 53.4 grams of a solutionof titanium isopropoxide in n-butanol were charged into a 68.13 liter(18-gallon) batch reactor with intermeshing spiral agitators and adistillation column. The agitator was operated forward for 50 minutesand then reversed for 10 minutes. The internal temperature was increasedto 200° C. and held for 2 hours. The temperature was then increased to260° C. and maintained for 30 minutes. After this, the weight ofdistillate was recorded and the temperature was increased to 280° C.Upon reaching 280° C. the weight of distillate was again recorded. Theagitator was changed to switch directions every 6 minutes, and vacuumwas applied at 13 Torr/minute until full vacuum (0.5 Torr) was reachedand held for 45 minutes at 25 rpm. The copolyester polymer obtained thenwas immediately extruded, and chopped into pellets. The polymer had aninherent viscosity of 0.678 dL/g. Compositional analysis (by NMR) showedthe diol component of the copolyester consisted of 63.9 mole percentCHDM residues and 36.1 mole percent NPG residues. The color values wereas follows: L*82.58, a*−0.66, b*4.76.

Example 12

A copolyester having the composition 100T/38CHDM/62NPG was produced in abatch pilot plant reactor. DMT (10.669 kg, 23.5 pounds), NPG (6.220,13.7 pounds), CHDM (3.223, 7.1 pounds), and 53.4 grams of a solution oftitanium isopropoxide in n-butanol were charged into a 68.13 liter(18-gallon) batch reactor with intermeshing spiral agitators and adistillation column. The agitator was operated forward for 50 minutesand then reversed for 10 minutes. The internal temperature was increasedto 200° C. and maintained for 2 hours. The temperature was thenincreased to 260° C. and maintained for 30 minutes. After this, theweight of distillate was recorded and the temperature was increased to280° C. Upon reaching 280° C. the weight of distillate was againrecorded. The agitator was changed to switch directions every 6 minutes,and vacuum was applied at 13 Torr/minute until full vacuum (0.5 Torr)was reached and maintained for 45 minutes at 25 rpm. The copolyesterpolymer obtained then was immediately extruded and chopped into pellets.The polymer had an inherent viscosity of 0.692 dL/g. Compositionalanalysis (by NMR) showed the diol component of the copolyester contained38.1 mole percent CHDM residues and 61.9 mole percent NPG residues. Thecolor values were as follows: L*83.04, a*−0.39, b*4.60.

The hydrolytic stability of the following amorphous copolyester polymerswas compared:

-   Polymers I and II: Same as Copolyesters I and II defined above.-   Polymer V: Copolyester of Example 11-   Polymer IV: Copolyester of Example 12    The procedure used in determining loss in molecular weight as a    result of hydrolysis involved placing a sample of the copolyester    into the barrel of a capillary rheometer and then heating to either    250° C. or 280° C. and holding for the specified time. The sample    was removed, after this treatment, and the molecular weight was    determined by standard size exclusion chromatography. The molecular    weight loss was calculated from the equation 1—M_(w)/M_(o) where    M_(w) is the molecular weight after treatment and M_(o) is the    original molecular weight. The higher the number the greater the    weight loss. The values listed in the “hydrolysis” rows are undried    samples, while those listed in the “thermal” rows refer to samples    dried at 60° C. for 48 hours at a vacuum of approximately 5 Torr.    The results are shown in Table III.

TABLE III Molecular Weight Loss Melt Melt Polymer Polymer PolymerPolymer Temp Time I II V VI Hydrolysis 250 5 0.24 0.1 0.05 0.05Hydrolysis 250 7 0.32 0.15 0.05 0.02 Hydrolysis 250 10 0.43 0.22 0.070.01 Hydrolysis 250 15 0.57 0.28 0.11 0.05 Thermal 250 5 0.02 0.02 0.080 Thermal 250 7 0.03 0.01 0.08 0.08 Thermal 250 10 0.02 0.02 0.12 0.05Thermal 250 15 0.02 0.03 0.09 0.07 Hydrolysis 280 5 0.47 0.24 0.07 0Hydrolysis 280 7 0.61 0.36 0.07 0.02 Hydrolysis 280 10 0.68 0.44 0.070.03 Hydrolysis 280 15 0.67 0.57 0.15 0.07 Thermal 280 5 0.07 0.08 0.130.1 Thermal 280 7 0.07 0.07 0.16 0.13 Thermal 280 10 0.06 0.06 0.2 0.16Thermal 280 15 0.1 0.08 0.22 0.19

Example 13

A copolyester having the composition 100T/49CHDM/51NPG was prepared. DMT(97 g, 0.5 moles), NPG (48.9 g, 0.47 moles), CHDM (40.7 g, 0.28 moles),and 1.26 ml of a solution containing 15 g of titanium tetraisopropoxidein 250 ml of n-butanol were added to a 500 ml single neck round bottomflask and reacted and polymerized according to the procedure describedin Example 1. The inherent viscosity of the polymer was 0.49 dL/g. Thepolymer had a 2^(nd) cycle Tg of 82.2° C. with no crystalline meltingpoint observed, and compositional analysis showed the diol component ofthe copolyester consisted of 49 mole percent CHDM and 51 mole percentNPG residues.

The procedure of Example 13 was repeated eight times to obtainsufficient polymer for molding and evaluation. The NMR composition (molepercent), inherent viscosity (dL/g) and 2^(nd) cycle DSC Tg (° C.) ofeach of the polymers obtained from the repetitions are shown below. Thecopolyesters obtained from Example 13 and the repetitions thereof werecombined and mixed prior to molding.

Composition IV 2^(nd) cycle DSC Tg T, 50NPG, 50CHDM 0.52 83.4 T, 50NPG,50CHDM 0.51 83.2 T, 51NPG, 49CHDM 0.52 83.1 T, 50NPG, 50CHDM 0.50 83.3T, 50NPG, 50CHDM 0.51 82.8 T, 51NPG, 49CHDM 0.51 82.2 T, 50NPG, 50CHDM0.52 82.3 T, 50NPG, 50CHDM 0.52 82.5

Example 14

A copolyester having the composition 100T/50CHDM/50NPG was prepared. DMT(97 g, 0.5 moles), NPG (48.9 g, 0.47 moles), CHDM (40.7 g, 0.28 moles),and 1.26 ml of a solution containing 15 g of titanium tetraisopropoxidein 250 ml of n-butanol were added to a 500 ml single neck round bottomflask and reacted and polymerized according to the procedure describedin Example 1. The inherent viscosity of the polymer was 0.56 dL/g. Thepolymer had a 2^(nd) cycle Tg of 84° C. with no crystalline meltingpoint observed, and compositional analysis showed the diol component ofthe copolyester consisted of 50 mole percent CHDM and 50 mole percentNPG residues.

The procedure of Example 14 was repeated six times to obtain sufficientpolymer for molding and evaluation. The NMR composition (mole percent),inherent viscosity (dL/g) and 2^(nd) cycle DSC Tg (° C.) of each of thepolymers obtained from the repetitions are shown below. The copolyestersobtained from Example 14 and the repetitions thereof were combined andmixed prior to molding.

Composition IV 2^(nd) cycle DSC Tg T, 50NPG, 50CHDM 0.54 83.3 T, 50NPG,50CHDM 0.55 82.7 T, 50NPG, 50CHDM 0.54 83.9 T, 50NPG, 50CHDM 0.56 83.6T, 50NPG, 50CHDM 0.56 83.2 T, 49NPG, 51CHDM 0.54 82.8

Example 15

A copolyester having the composition 100T/49CHDM/51NPG was produced in abatch pilot plant reactor. DMT (10.646 kg, 23.5 pounds), NPG (6.214 kg,13.7 pounds), CHDM (3.234 kg, 7.1 pounds), and 26.7 grams of a solutionof titanium isopropoxide in n-butanol were charged into a 68.13 liter(18-gallon) batch reactor with intermeshing spiral agitators and adistillation column. The agitator was operated forward for 50 minutesand then reversed for 10 minutes. The internal temperature was increasedto 200° C. and held for 2 hours. The temperature was then increased to260° C. and maintained for 30 minutes. After this, the weight ofdistillate was recorded and the temperature was increased to 280° C.Upon reaching 280° C. the weight of distillate was again recorded. Theagitator was changed to switch directions every 6 minutes, and vacuumwas applied at 13 Torr/minute until full vacuum (0.5 Torr) was reachedand held until a 750 wattmeter increase or a peak. The copolyesterpolymer obtained then was immediately extruded, and chopped intopellets. The polymer had an inherent viscosity of 0.77 dL/g.Compositional analysis (by NMR) showed the diol component of thecopolyester consisted of 49.3 mole percent CHDM residues and 50.7 molepercent NPG residues.

Comparative Example 1

A copolyester having the composition 100T/48CHDM/52NPG was prepared. DMT(97.0 g, 0.5 moles), NPG (48.9 g, 0.47 moles), CHDM (40.7 g, 0.28moles), and 0.63 ml of a solution containing 15 g of titaniumtetraisopropoxide in 250 ml of n-butanol were added to a 500 ml singleneck round bottom flask. The flask was immersed in a Belmont metal baththat was preheated to 200° C. Immediately after the flask was immersedthe temperature was increased to and held at 220° C. for 2.5 hours. Thetemperature then was increased to and held at 260° C. for 30 minutes.After this time the theoretical methanol was collected. The pressure inthe flask was then reduced from atmospheric to 0.5 Torr. When thepressure had been reduced to 0.5 Torr (6 minutes), the temperature setpoint was then raised to 280° C. Approximately 5 minutes after raisingthe temperature set point to 280° C., stirring was reduced from 200 rpmto 100 rpm and held for 10 minutes. The vacuum was discontinued andnitrogen was bled into the flask. The polymer was allowed to solidify bycooling to a temperature below Tg, removed from the flask and thenground to pass through a 3 mm screen. The inherent viscosity of thepolymer was 0.29 dL/g. The polymer had a 2^(nd) cycle DSC Tg of 75.4° C.and compositional analysis by NMR showed the diol component of thecopolyester consisted of 48 mole percent CHDM and 52 mole percent NPGresidues.

The procedure of Comparative Example 1 was repeated eight times toobtain sufficient polymer for molding and evaluation. The NMRcomposition (mole percent), inherent viscosity (dL/g) and 2^(nd) cycleDSC Tg (° C.) of each of the polymers obtained from the repetitions ofComparative Example 1 are shown below. The copolyesters obtained fromComparative Example 1 and the repetitions thereof were combined andmixed prior to molding.

Composition IV 2^(nd) cycle DSC Tg T, 52NPG, 48CHDM 0.31 77.1 T, 52NPG,48CHDM 0.31 75.6 T, 52NPG, 48CHDM 0.37 79.1 T, 52NPG, 48CHDM 0.36 78.4T, 52NPG, 48CHDM 0.29 74.0 T, 52NPG, 48CHDM 0.34 78.5 T, 52NPG, 48CHDM0.34 78.2 T, 52NPG, 48CHDM 0.33 78.1

Standard tensile test bars (ASTM-D638) were prepared by injectionmolding each of the copolyesters Examples 13, 14, 15 and ComparativeExample 1 and subjected to tensile testing according to ASTM D638,flexural testing according to ASTM D790 and Unotched Izod ImpactStrength at 23° C. according to ASTM D256. The results of these testsare shown in Table IV wherein the values given for Yield Strain andBreak Strain are percentages, Yield Stress, Break Stress and Modulus aregiven in pounds per square inch. The inherent viscosities (IV, dL/g)were measured prior to molding.

TABLE IV Example 13 14 15 C-1 IV 0.51 0.56 0.77 0.33 Flexural YieldStrain 5.01 5.1 4.8 1.96 Yield Stress 9380 9313 9495 4888 Modulus 269738265031 278381 252056 Tensile Yield Strain 5.36 5.24 5.2 2.4 Yield Stress6493 6526 6461 3534 Break Stress 4921 7518 8695 3534 Break Strain 92.98180 180.16 2.4 Elongation to break Izod Unnotched 80% No Break 80% NoBreak 100% No Break 100% Break >16 ft-lb/inch >16 ft-lb/inch >16ft-lb/inch 0.51 ft-lb/inchThe low molecular weight copolyester of Comparative Example 1 (IV=0.33),similar to the copolyester exemplified in U.S. Pat. No. 4,551,403,exhibits an elongation to break of only 2.4% whereas the elongation tobreak of the Example 13 copolyester (IV=0.51) is 92.98%. Theseelongation to break values go to 180% for copolyesters having IV's of0.56 and 0.77. The elongation to break values demonstrate the excellentand useful mechanical properties for the copolyesters having IV's ofgreater than 0.5 dL/g. In addition, the unnotched Izod impact value forthe copolyester of Comparative Example 1 was only 0.51 foot-pounds perinch with 100% of the test bars breaking during the test. This unnotchedIzod impact value indicate that the Comparative Example 1 copolyester isa very brittle material and is contrasted to the 80% no break for thecopolyesters of Examples 13 and 14 and 100% no break for the copolyesterof Example 15. The higher molecular weight copolyesters of Examples 13,14 and 15 therefore are non-brittle, tough useful materials. Thecopolyester of Comparative Example 1 was so brittle that it was almostimpossible to mold test bars for the mechanical property evaluation.Thus, the low molecular weight copolyester of Comparative Example 1 isof no value as a molding or extrusion copolyester. In contract, thecopolyesters having IV's greater than 0.5 dL/g have excellent mechanicalproperties.

Example 16

A copolyester comprising a diacid component consisting of 100 molepercent terephthalic acid residues and a diol component consisting of 60mole percent CHDM residues and 40 mole percent NPG residues (hereinafterreferenced as 100T/60CHDM/40NPG) was melt-phase polymerized in a 65gallon (245 liter) stainless steel batch reactor with intermeshingspiral agitators. To the reactor was added 39.64 kg (87.39 pounds, 204.5moles) of dimethyl terephthalate, 11.48 kg (25.30 pounds, 110.4 moles)of neopentyl glycol (NPG), 28.25 kg (62.27 pounds, 196.3 moles) of1,4-cyclohexanedimethanol (CHDM) and 112.56 grams of a butanol solutioncontaining the titanium catalyst. The reactor was heated to 200° C. andheld for 2 hours with agitation at 25 RPM. The temperature was increasedto 260° C. and held for 30 minutes. The temperature was increased to270° C. and the pressure was reduced at a rate of 13 torr per minute tofull vacuum. After the vacuum reached <4000 microns (<4 torr), theseconditions were held for 1 hour and 15 minutes at 25 RPM. The RPM wasreduced to 15 RPM and the conditions held to a wattmeter peak. Thepressure was increased to atmospheric with nitrogen and the copolymerwas pelletized.

Bottles were prepared using an 80 mm Bekum H-121 continuous extrusionblow molding machine fitted with a barrier screw. The copolymer had amelt phase inherent viscosity (IV) of 0.719, color values of L*=55.20,a*=0.28, b*=17.76, and a composition by Nuclear Magnetic Resonance (NMR)of 100T/60CHDM40NPG. The materials were dried for 8 hours at 65° C.(150° F.) prior to extrusion. The extruder was run at 21 revolutions perminute (RPM) using a 200° C. (392° F.) barrel temperature and a 190° C.(375° F.) head temperature. The temperature of the melt was 218° C.(425° F.), measured by inserting a melt probe directly into the parison5 mm out from the die. The materials were extruded into water bottleshaving a volume of 3.785 liters (1 U.S. gallon), using a 100 mm die. Thebottles weighed between 140 and 190 grams.

Example 17

A copolyester comprising a diacid component consisting of 100 molepercent terephthalic acid residues and a diol component consisting of 56mole percent CHDM residues and 44 mole percent NPG residues (hereinafterreferenced as 100T/56CHDM/44NPG) was melt-phase polymerized in a 65gallon (245 liter) stainless steel batch reactor with intermeshingspiral agitators. To the reactor was added 39.64 kg (87.39 pounds, 204.5moles) of dimethyl terephthalate, 11.48 kg (25.30 pounds, 110.4 moles)of neopentyl glycol (NPG), 28.25 kg (62.27 pounds, 196.3 moles) of1,4-cyclohexanedimethanol (CHDM) and 112.56 grams of a butanol solutioncontaining the titanium catalyst. The reactor was heated to 200° C. andheld for 2 hours with agitation at 25 RPM. The temperature was increasedto 260° C. and held for 30 minutes. The temperature was increased to270° C. and the pressure was reduced at a rate of 13 torr per minute tofull vacuum. After the vacuum reached <4000 microns (<4 torr), theseconditions were held for 1 hour and 15 minutes at 25 RPM. The RPM wasreduced to 15 RPM and the conditions held to a wattmeter peak. Thepressure was increased to atmospheric with nitrogen and the copolymerwas pelletized.

Bottles were prepared using an 80 mm Bekum H-121 continuous extrusionblow molding machine fitted with a barrier screw containing a Maddockmixing section. The copolymer had a melt phase inherent viscosity (IV)of 0.725, color values of L*=50.50, a*=−2.46, b*=2.50, and a compositionby Nuclear Magnetic Resonance (NMR) of 100T/56CHDM44NPG. The materialswere dried for 8 hours at 65° C. (150° F.) prior to extrusion. Theextruder was run at 10 revolutions per minute (RPM) using a 190° C.(375° F.) barrel temperature and a 185° C. (365° F.) head temperature.The temperature of the melt was 212° C. (413° F.), measured by insertinga melt probe directly into the parison 5 mm out from the die. Thematerials were extruded into handleware juice bottles having a volume of1.89 liters (64 ounces), using a 70 mm die. The bottles weighed between70 and 80 grams.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

1. A shaped article having improved resistance to degradation fromexposure to lipids wherein the shaped article comprises an amorphouscopolyester having an inherent viscosity (IV) of about 0.5 to 1.1 dL/gmeasured at a temperature of 25° C. at 0.5 g/dL concentration in asolvent mixture of symmetric tetrachloroethane and phenol having aweight ratio of symmetric tetrachloroethane to phenol of 2:3 andcomprising: (1) a diacid component comprising about 90 to 100 molepercent terephthalic acid residues and 0 to about 10 mole percentisophthalic acid residues; and (2) a diol component consistingessentially of about 30 to about 70 mole percent1,4-cyclohexanedimethanol residues and about 70 to about 30 mole percentneopentyl glycol residues; wherein the amorphous copolyesters comprises100 mole percent diacid component and 100 mole percent diol component.2. The shaped article of claim 1 wherein the article is fabricated byextrusion blow molding.
 3. The shaped article of claim 1 wherein thediacid component consists essentially of at least 95 mole percentterephthalic acid residues.
 4. The shaped article of claim 1 wherein thediacid component consists essentially of 100 mole percent terephthalicacid residues.
 5. The shaped article of claim 1 wherein the diolcomponent of the amorphous copolyester consists essentially of about 35to about 60 mole percent 1,4-cyclohexanedimethanol residues and about 40to about 65 mole percent neopentyl glycol residues.
 6. The shapedarticle of claim 5 wherein the diacid component consists essentially ofat least 95 mole percent terephthalic acid residues.
 7. The shapedarticle of claim 5 wherein the diacid component consists essentially of100 mole percent terephthalic acid.
 8. The shaped article of claim 1which is transparent medical device.
 9. The medical device of claim 8which is in the shape of a tube.
 10. The medical device of claim 8 whichis in the shape of a connector.
 11. The medical device of claim 8 whichis in the shape of a pump housing.
 12. A medical article for contactingsolutions containing lipids, the article comprising an amorphouscopolyester having an inherent viscosity (IV) of about 0.5 to 1.1 dL/gmeasured at a temperature of 25° C. at 0.5 g/dL concentration in asolvent mixture of symmetric tetrachloroethane and phenol having aweight ratio of symmetric tetrachloroethane to phenol of 2:3 comprising:(1) a diacid component comprising about 90 to 100 mole percentterephthalic acid residues and 0 to about 10 mole percent isophthalicacid residues; and (2) a diol component consisting essentially of about30 to about 70 mole percent 1,4-cyclohexanedimethanol residues and about70 to about 30 mole percent neopentyl glycol residues; wherein theamorphous copolyesters comprises 100 mole percent diacid component and100 mole percent diol component.
 13. The medical article of claim 12wherein the diacid component consists essentially of at least 95 molepercent terephthalic acid residues.
 14. The medical article of claim 12wherein the diacid component consists essentially of 100 mole percentterephthalic acid residues.
 15. A medical article for contactingsolutions containing lipids, the article comprising an amorphouscopolyester having an inherent viscosity (IV) of about 0.6 to 1.1 dL/gmeasured at a temperature of 25° C. at 0.5 g/dL concentration in asolvent mixture of symmetric tetrachloroethane and phenol having aweight ratio of symmetric tetrachloroethane to phenol of 2:3 comprising:(1) a diacid component consisting essentially of terephthalic acidresidues; and (2) a diol component consisting essentially of about 30 toabout 70 mole percent 1,4-cyclohexanedimethanol residues and about 70 toabout 30 mole percent neopentyl glycol residues; wherein the amorphouscopolyesters comprises 100 mole percent diacid component and 100 molepercent diol component.
 16. The medical article of claim 15 wherein thearticle is a tube, connector or pump housing.
 17. A method of meltprocessing an amorphous copolyester having a moisture content prior tomelt processing of 0.02 weight % or more comprising: (a) prior to meltprocessing, performing a minimal drying or no drying of the copolyestersuch that the copolyester has a moisture content of 0.02 weight % ormore prior to melt processing, and (b) melt processing the copolyester,wherein the copolyester has an inherent viscosity (IV) of about 0.5 to1.1 dL/g measured at a temperature of 25° C. at 0.5 g/dL concentrationin a solvent mixture of symmetric tetrachloroethane and phenol having aweight ratio of symmetric tetrachloroethane to phenol of 2:3 andconsists essentially of an acid component of residues of at least 90mole percent terephthalic acid and a diol component consistingessentially of about 30 to about 70 mole percent1,4-cyclohexanedimethanol residues and about 70 to about 30 mole percentneopentyl glycol residues, based on 100 mole percent acid component and100 mole percent glycol component.
 18. The method of claim 17 whereinthe diol component consists essentially of about 30 to less than 70 molepercent 1,4-cyclohexanedimethanol residues and about 70 to about 30 molepercent neopentyl glycol residues.
 19. The method of claim 17 whereinthe acid component has residues of at least 95 mole percent terephthalicacid.
 20. The method of claim 17 wherein the acid component has residuesof 100 mole percent terephthalic acid.
 21. The method of claim 17wherein prior to melt processing, the minimal drying is performed,wherein the minimal drying is by conventional methods for less than 2hours at 60 to 100° C.
 22. The method of claim 17 wherein prior to meltprocessing, the minimal drying is performed, wherein the minimal dryinguses a desiccant bed with forced dehumidified air at 60° C. to 100° C.23. The method of claim 17 wherein no drying of the copolyester isperformed prior to melt processing.